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Granite Countertops and Radiation

Recent news stories have raised concerns about the possibility of radiation coming from granite countertops.

Granite, as with other kinds of rocks and soils, contains some naturally occurring radioactive elements commonly referred to as Naturally Occurring Radioactive Material (NORM). NORM is made up of elements such as thorium, uranium, and potassium, which contribute to what scientists call “background” radiation. Background radiation is a combination of terrestrial and cosmic radiation that individuals are continuously exposed to as part of living on planet earth. In Texas, on average, we receive about 300 millirem each year from these sources. A person would receive approximately 20 millirem from a routine chest x-ray.

The amount of radioactivity in most granite is quite small. While it is possible to get a measurable level of direct radiation from some granite, in general it emits less radiation than we are regularly exposed to from background radiation. These levels are so low that they are not harmful to human health.

Radon is a naturally occurring radioactive gas that can be released during the decay of radioactive elements in granite countertops or can seep into homes from underground uranium deposits, and build up to higher than normal levels.(See: What is Radon?) Most areas of Texas are considered to be at a low risk level for high radon levels (See: The Texas Indoor Radon Survey), but it is still a good idea to test, and know for sure.

Texas Department of State Health Services, along with the U.S. EPA and the U.S. Surgeon General, encourages everyone to test their home for radon. (See: Where Do I Get a Radon Test Kit?)

What is Radon?

Radon is an odorless, colorless, radioactive gas that develops with the natural breakdown of uranium in soil and rock. Radon can migrate through permeable rocks and soils and eventually seep into buildings or be relased into the atmosphere. Radon is measured in units of picocuries per liter (pCi/l) of radon in the air.

What are the Health Risks Associated with Radon?

The only known health risk associated with Radon is the potential to develop lung cancer. In addition, smoking combined with radon exposure greatly increases the risk for developing lung cancer.

How are You Exposed to Radon?

Radon that seeps into homes may accumulate there and decay into radioactive, chemically reactive particles that attach themselves to dust in the home environment. If inhaled over a long period of time, these radioactive particles may cause damage to the lung tissues and increase the risk of developing lung cancer.

The Texas Indoor Radon Survey

In 1991, the Texas Department of Health, Bureau of Radiation Control (BRC) commissioned a statewide survey of indoor residential radon to determine the extent of the problem in Texas, and to identify potential "hot spots." When viewed on a statewide basis, the radon measurements from nearly 2,700 randomly selected Texas homes were relatively low -- averaging 1.0 pCi/l of air. The threshold of concern, according to the Environmental Protection Agency (EPA) guidelines is 4.0 pCi/l air.

Click on the picture of the coverfor the complete survey.2553KB - 26 pgs.

Is Radon a Problem in Texas?

In Texas, the average of radon in homes is within national norms; however, when examined on a county-by-county basis, several areas of Texas are identified where local geology is suspected of contributing to the potential for elevated levels of indoor radon.

The Panhandle area of Texas, especially those counties clustered in a band through its center, is shown to have moderate potential for indoor radon. This area of the state is the only area to report any sizable number of homes with radon levels above 20 pCi/l of air, but, on the average, these areas fall within the "Moderate Potential" zone.

Texas has no areas of "Highest Potential," according to the United States Environmental Protection Agency standards.

How Can I Test for Radon?

There are two principle radon testing methods for home use. The most commonly used method is the short-term charcoal canister test that passively absorbs small amounts of radon over 3-7 days. The canister is subsequently analyzed by an EPA-approved lab.

The other method is a long-term (one month - one year) alpha--track test that detects radiation from radon and is then analyzed by an EPA-approved lab.

Where Do I Get a Radon Test Kit?

Test kits might be found at your local hardware store for about $10 - $15, depending on the demand for kits in your particular area. You may also purchase test kits online from numerous private companies or through the National Radon Program Services (http://sosradon.org/).

Please note that if radon levels in the home exceed four (4) picocuries per liter of air (pCi/L) the EPA recommends that homeowners should take action. When using a short-term test kit, additional testing is recommended to confirm the high levels.